This invention relates generally to fuel filters employed in connection with internal combustion engines. More particularly, the present invention relates to replaceable fuel filter cartridges for removing foreign particles and/or separating water from the fuel supply system of an internal combustion engine.
Fuel filter systems to which the invention relates commonly employ a disposable filter cartridge which is replaced at pre-established intervals of filter usage. The replaceable cartridge is conventionally secured to a base which forms inlet and outlet connections between the cartridge and the fuel supply system. Numerous retention systems have been employed for securing the filter cartridge to the base and allowing removal of the cartridge for replacement purposes.
In U.S. Pat. No. 5,017,285, which is assigned to the assignee of the present invention, a disclosed fuel filter assembly comprises a base which mounts to the vehicle and a disposable filter cartridge which is suspended from the filter base. In this configuration, the cartridge is retained to the base by a threaded collar. The collar has a rim which retentatively engages against a protruding roll seam structure at the periphery of the cartridge housing. The cartridge is thus replaced by loosening the threaded collar and dismounting the filter cartridge.
In U.S. Pat. No. 5,203,994, which is assigned to the assignee of the present invention, the disposable filter cartridge is mounted to the base by a retainer collar. The base and the retainer collar have a pair of complementary spiral ramp-like structures. The retainer collar rotatably follows the ramp-like structures so that catches are positioned in slots of the base for locking the cartridge to the base. A spring biases the catch to the locked position. The spring is a spring washer which has an inscribed starlike configuration wherein one alternating set of spring leaves engages against the end of the cartridge and the second set is engageable against an adjacent surface of the base.
In U.S. Pat. No. 5,302,284, which is assigned to the assignee of the present invention, a disposable filter cartridge is retained to the base by means of a spring-loaded collar. The collar carries a wave spring and has followers which ascend a spiral ramp of the base to secure the disposable cartridge in a positive locked position.